multiple attachments in mail

hi friends,
i m developing a mail sending form on which there are typical fields like..to....from....subject....message..and a send button

there is also option for attachments..it is like following...

i have used a html file input control (<input type="file">)
i have put a dropdown list(with <select >)tag
when i click on browse button of the file input control,
and select a file ..it is added to the <select> list....
user can add more than one files ...

now i want to do like that, all the added file in <select> must be attached to mail...

so how can i do this....do i need to upload these files to server before i can attach them....if yes then how can i do that...please can anybody help me...its very urgent.....

thank u